The Benefits of Aspheric Lenses
Aspheric lenses, when used in both eyeglasses and contact lenses have many benefits that will sound pretty simple. The truth is, a lot of research had to go in to the development of them and for each power of lens the aspheric curves will be unique.
To imagine a regular lens, picture a section of ball, perfectly round and smooth. That is a spherical lens. The beauty of spherical lenses is that they are simple. If the front surface of the lens has a +2.00 sphere and the back surface has no correction, the lens is a +2.00 all over the lens.
The issue with this when it comes to vision is that our corneas are not perfectly spherical, nor are our eyes. Therefore this type of lens will give us distortion, known as aberrations. Another concern is that lenses designed in this fashion can tend to be very thick and heavy.
In come aspheric lenses and aspheric optics. Aspheric basically means that the lens has a curve that is gradually adjusted from center to edge. Think of it as if you simply smushed the lens surface down a little, so it gradually becomes flatter towards the edge.
Optically the benefit is less distortion. Light that enters the lenses from the periphery will be in more focus than that with a spherical lens.
As far as comfort and style, aspheric lenses are much thinner and lighter than their spherical counterparts.
When we are dealing with low powered prescriptions, aspheric lenses do not make all that much of a difference. However in higher powered lenses they are a must. When it comes to contact lenses, aspheric lenses are used more for optics, as there are other methods to relieve contacts from mass and potential edge thickness.